1. Field of the Invention
The present invention relates to a technique for mixing heterogeneous solutions by using a small-size device in order to analyze the chemical property of one of the solutions from the result of reaction of the heterogeneous solutions.
2. Description of the Related Art
A chemical analysis system makes a sample solution react chemically or biochemically with a reagent solution, and analyzes the result of the reaction. Thus, the system measures the chemical property of the sample solution. This chemical analysis system is used for a blood test, infection diagnosis, genetic diagnosis, genetic analysis, or observation of gene synthesis, mechanofusion, coupling reaction, organometallic reaction, catalytic synthesis reaction, electrolytic synthesis reaction, acid alkali decomposition reaction and electrolysis reaction. For example, the chemical analysis system makes a sample solution such as serum and urine of a subject react chemically or biochemically with a reagent solution, performs photometry, and analyzes various items such as cholesterol level, triglyceride level, blood glucose level, and GOT activity level.
For this purpose, this chemical analysis system dispenses a sample and mixes with a reagent solution, and makes the sample solution and the reagent solution react. Then, the chemical analysis system detects the result of the reaction, and converts data on the reaction into a physical quantity indicative of the chemical property of the sample solution. Finally, the chemical analysis system outputs the obtained physical quantity in a visible form. A typical example is a chemical analysis system disclosed in Japanese patent publication No. 3300704, which measures the concentration or activity of a substance or enzyme within a test sample. This chemical analysis system automatically dispenses the test sample and a reagent appropriate for a measurement item into a reaction tube by certain quantities, stirs and mixes, and then makes them react at a certain temperature. Then, on the basis of measurement of a change in color tone caused by the reaction, the chemical analysis system measures the concentration or activity of the substance or enzyme within the test sample.
In recent years, the chemical analysis system has become smaller in size. For example, there have been proposed a portable blood analyzer that utilizes a cassette-type channel disclosed in Japanese patent publication No. 2995088, and a mobile chemical examination device using a sheet-like microreactor disclosed in Japanese unexamined patent publication No. 2002-340911.
In general, the microchemical analysis system delivers a sample solution and a reagent solution in the merged stage through a common channel, thereby mixing the sample solution and the reagent solution while delivering through the channel by utilizing the molecular diffusion effect. However, in order to completely mix within the channel, this channel needs to be sufficiently long. Therefore, such a mechanism is an impediment on size reduction. Moreover, when the solutions are mixed gradually while being delivered within the channel, there is the fear that the result of reaction is measured while the reaction is incomplete, which is more likely to cause an error in result of the reaction.
Consequently, various types of mixing acceleration means may be installed within a channel in order to accelerate mixture within the channel. Examples of the mixing acceleration means include a technique disclosed in Japanese unexamined patent publication No. 2006-153785, which transforms part of a channel in which a sample solution and a reagent solution are merged and delivered to apply a transforming force as a stirring force. Another example is a technique disclosed in U.S. unexamined patent publication No. 2004/0115097, which utilizes surface acoustic waves that are excited on the surface of a piezoelectric body by distortion of the surface of the piezoelectric body. In such microchemical analysis systems, the mixing acceleration means is provided within a channel that delivers a sample solution and a reagent solution in the merged state.
A technique of providing mixing acceleration means in the channel to accelerate mixture has been developed in existing microchemical analysis systems. However, the mixing acceleration means provided in the channel may cause a problem of insufficient stirring effect. This is because a sample solution and a reagent solution are delivered spreading inside a channel and, when mixing acceleration means is situated in a section of the channel, a stirring force is applied only to part of the sample solution and reagent solution passing through the section provided with the mixing acceleration means. In other words, it is impossible totally stir the sample solution and the reagent solution. Moreover, it takes a long time to stir fully.
Even if the mixing acceleration means is provided, it is the same as gradually mixing that mixture of the solutions is accelerated for every part of the solutions passing through the mixing acceleration means. Therefore, the reaction may become nonuniform, and the reaction system may differ, with the result that an error arises in result of the reaction.